Inside the housing case housing the power transmission element (a gear and the rotation axis) which transmits the power, there is formed a main oil passage in an inside from an axis end face thereof as the rotation axis, and also formed a branched oil passage extending outward in a radial direction from the main oil passage thereof, and opening to an outside from an outer circumferential face thereof. The lubricating oil flipped up by the gear inside the housing case thereof is collected, and the lubricating oil thereof is led to an opening side of the main oil passage of the rotation axis. Thereby, the lubricating oil led to the main oil passage is sent outward in the radial direction of the rotation axis from the branched oil passage, and the lubricating oil thereof is used for lubricating the gear again. Consequently, in order to realize such a lubricating-oil circulation structure, conventionally, there is disposed the lubricating-oil collection guide tool inside the housing case.
As for the lubricating-oil collection guide tool, as shown in Patent Document 1, there is proposed a lubricating-oil collection guide tool, wherein an oil-collection container disposed upward in a series of gear groups inside the housing case, and receiving an oil flipped up by the gears; a guide member disposed in an axis end of the rotation axis inside the housing case, and guiding the lubricating oil into the main oil passage of the rotation axis; and an oil-passage member communicating the guide member and the oil-collection container, and leading the lubricating oil collected in the oil-collection container to the guide member, are integrally molded using a resin material. When using the above tool, compared to a case of using the lubricating-oil collection guide tool wherein the oil-collection container, the guide member, and the like are respectively separate bodies (for example, Patent Document 2), the number of an assembly can be reduced so as to be capable of facilitating the assembly. Also, there is no need for forming the oil passage in the housing case so as to be capable of reducing a load for a process relative to the housing case.